Properties of isocalar-pair condensates

TL;DR

This paper investigates the ground state properties of neutron-proton pairs under isoscalar pairing, revealing a spin-aligned state rather than the traditionally expected paired state, and provides an analytic model for this behavior.

Contribution

It introduces an analytic model for isoscalar P (J=1) pairs mapped onto p bosons, explaining the spin alignment in the ground state of neutron-proton pairs.

Findings

Ground state is spin-aligned, J=n, not J=0.

Model provides an approximate analytic solution for isoscalar pairing.

Highlights the importance of spin alignment in isoscalar-pair condensates.

Abstract

It is pointed out that the ground state of n neutrons and n protons in a single-j shell, interacting through an isoscalar (T=0) pairing force, is not paired, J=0, but rather spin-aligned, J=n. This observation is explained in the context of a model of isoscalar P (J=1) pairs, which is mapped onto a system of p bosons, leading to an approximate analytic solution of the isoscalar-pairing limit in jj coupling.